High speed stepping apparatus



June 30, 1964 GROTH 3,139,549

HIGH SPEED STEPPING APPARATUS Filed Dec. 18, 1959 2 Sheets-Sheet lINVENTOR.

HANS FA. GROTH AGENT June 30, 1964 H. F. A. GROTH HIGH SPEED STEPPINGAPPARATUS INVENTOR.

HANS EA GROTH 2 Sheets-Sheet 2 Filed Dec. 18, 1959 United States Patentice I This invention relates to stepping mechanisms, and moreparticularly, to extremely high speed electrically controlled mechanismsof the step-by-step type which are operable in response to successiveelectrical actuating impulses.

Prior art stepping mechanisms have certain limitations,

and disadvantages which have in the past tended to prevent theattainment of relatively high operating speeds. One of the more commonproblems with known stepping mechanisms is that the relative operatingspeeds generally are derived for the most part from the actuation of anelectromagnet or a solenoid or from the stored energy of a spring whichis or may be cocked by such electromechanical components. Since the loaddetermines the size of the spring and of the armature, the more massthere is to be driven the stronger the spring and armature must be forthis driving purpose and therefore the larger and more powerful theelectromagnet or the solenoid must be to drive or to cock the spring.

Stepping mechanisms of the foregoing type have been relatively large andbulky due to the driving forces involved.

Other problems with known stepping mechanisms include the high mass ofthe driven parts and the size and mass of the mechanism used to permitthe device to advance step-by-step, i.e., escapement arm, pallet, pawls,etc.

In view of the foregoing it is an important object of the presentinvention to provide a simple eflicient and relatively inexpensivestepping mechanism which avoids the foregoing limitations and whichattains extremely high operating speeds.

It is another object of the invention to provide an extremely high speedstepping mechanism in which the driving force is independent of thestepping control function of the mechanism.

It is still another object of the invention to provide a step-by-stepmechanism the operation of which may be synchronous or asynchronous.

It is still another object of the invention to provide a high speed lowinertia stepping mechanism wherein a moving coil actuated escapementmechanism controls a high break away torque and checks a low impacttorque when the mechanism is stopped.

In accordance with the above objects and first briefly described herein,the present invention provides a novel extremely high speed steppingmechanism including a rotatable drive shaft subject to a constantunidirectional torque supplied thereto. Rotation of the drive shaft iscontrolled by a double faced escapement wheel which is releasably,radially engaged by an electromagnetic moving coil actuated latch. Thelatch is permitted a freedom of movement in a direction parallel to theaxis of rotation of said escapement and in a radial direction forpurposes of resetting the mechanism to zero. Axiallateral movement ofthe latch permits the'escapement wheel to rotatean increment at a timeunder the application of the constant torque.

Patented June 30, 1964 In the preferred embodiment of the invention,described in detail hereinafter, the stepping mechanism is operablyassociated with a commutator type rotary switch apparatus wherein aninsulating hub secured to and rotatable with the drive shaft of thestepping mechanism carries at one end thereof a plurality of radiallymounted conductive wiper arms which are disposed between a pair ofparallel spaced plates. These plates have a plurality of etched circuitmembers such as slip-rings and parallel busses confronting the wiperarms. The step switch may be caused to move step-by-stepcontinuously andsuccessively over the etched circuit busses in response to appliedelectrical pulses at extremely high speed. An electromagneticallycontrolled reset device permits the mechanism to return to a selectedstarting position for the initiation of another switching operation.

The features of the invention which are believed to be novel are setforth with particularity in the following specification and in theappended claims. The invention itself, however, both as to itsorganization and operation, together with further objects and advantagesthereof, may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a side elevational View of the invention partially in sectionwith portions thereof broken away to expose some of the structuralfeatures of the invention;

. FIG. 2 is a detail view drawn to an enlarged scale of a portion of thecontrol mechanism of the present invention;

FIG. 3 is a front elevational view of the invention with certainportions broken away to expose the escapement wheel and the commutatormechanism employed therewith;

FIG. 4 is a compound view greatly enlarged of a portion of theescapement wheel and latch illustrating the manner in which the wheelescapes a tooth at a time;

FIG. 5 is an isometric view of a portion of the electromagnetic controlmechanism of the invention drawn to an enlarged scale to more clearlyillustrate the novel structural combination; and

FIG. 6 is an enlarged detail view of the escapement mechanismillustrating two of its operational positions.

Referring now more particularly to the drawings and to the variousfigures thereof which will be discussed simultaneously, it is seen thatthe novel high speed stepping mechanism of the present inventionincludes a plurality of sub-assemblies which-are operably interconnectedto form a unitary structure. The illustrated embodiment is shownoperatively associated with a rotary stepping switch but it is to beunderstood thatthe novel step-bystep mechanism herein described andillustrated may find application in other and different environments,and the scope of the invention is thus not to be considered as limitedto stepping switches per se. The present inven tive concept is equallyapplicable to any apparatus wherein it is desired to move a machineelement rotatively or laterally in discrete timed intervals at extremelyhigh speed under the control of electric pulses.

As shown in'FIG. 1, the high speed rotary steppingswitch and resettingmechanism of the present invention includes a central or commonrotatable shaft 10 concentrically mounted within a spacing sleeve 12,journalled in bearing members 14-14 disposed at opposite ends of thesleeve 12 and press fitted ,or otherwise mounted in wall members 16 and18. In the preferred embodiment, the members 16 and 18 may be formed ofsoft iron or other magnetizable material as will be explained later on.The shaft 10 is of sufficient length, as shown, to provide a support forvarious additional elements which are employed with the presentinvention and described hereinafter.

Intermediate the ends of shaft 10, adjacent wall member 18 and disposedthereon prior to assembly of the complete apparatus, is an escapementwheel 20 which may be secured to shaft 10 in any well known manner, asby means of a dowel pin 22, so that the escapement wheel is obliged torotate with the shaft. The escapement wheel, as seen in FIG. 1, isdouble faced, i.e. each side face of the wheel is provided with aplurality of tooth-like projections 24 formed along the opposite peripheries thereof such as by being stamped, pressed, cut or moldedintegral with the peripheral web of the wheel. For purposes to beexplained presently, the projections 24 on one peripheral edge of thewheel 20 are off-set or displaced angularly with respect to theprojections 24 on the opposite peripheral edge of the wheel. The amountor degree of such off-set or displacement is a matter of design,however, in the illustrated embodiment the teeth on opposite sides ofthe escapement wheel are off-set angularly by one-half the circularpitch of the teeth on one side. In this manner each quandrant of thewheel, as seen in FIG. 3, may be provided with nine teeth or a total ofthirty-six teeth for each side of the wheel, seventy-two teeth in all.

For a purpose to be explained hereinafter, the escapement wheel 2% isprovided with a relatively long projecting tooth 26, FIGS. 1 and 2,formed in a suitable manner out of the web of the wheel and extendingoutwardly away from the periphery of the wheel a substantial distance.Projection 26 is adapted to provide a zeroizing abutment or home stopfor the escapement Wheel 20, and operates to detent the wheel when it isreset, in a manner to be explained presently.

Shaft 10 is adapted to be constantly rotated at a relatively high rateof speed. T this end, a friction coupling or slip clutch 28 is providedin order to couple a con stantly rotating input power shaft 30 to shafttill. Slip clutch 28 may comprise any suitable well known type of slipclutch, however, for purposes of the present description a magnetichysteresis clutch is illustrated. The clutch includes an inputcup-shaped member 32 secured to shaft 3% as by the pin 34, and carries asubstantially circular permanent magnet member 36 centrally disposedwithin the member 32 and forming, together with the upstanding wall 37thereof, an air gap 38. Magnet 36 which may be press fitted to a hub 39integral with member 32 may include a number of magnetic polarcastellations 40 forming alternate north and south poles in a mannerwell known in the magnetic clutch art. Output member 42, alsocup-shaped, is secured to a collar 43 attached to one end of shaft itsuch that the cylindrical portion 44 of member 42 is rotatablesubstantially wholly within the air gap 33. In this construction acomplete magnetic loop is provided by means of the magnet 36, drive cup32 and air gap 38 within which the Wall 44 of member 42 is rotatable.

It should be apparent from the foregoing that with shaft 31) rotating, acontinuous torque is applied to shaft it), through coupling 28, so thatshaft 10 will rotate unless it is restrained by some external force,such for example, as the control mechanism to be described hereinafter.

Disposed between the two frame or wall forming members 16 and 18 is amagnetic structure 46 including a hollow cylindrical permanent magnet 48having a substantially solid centrally located cylindrical ferrous orother type magnetic core 50. The magnetic structure may be integral withor suitably attached to the wall member 16. The rightward rim portion ofmagnet 48 abuts the wall member 18 and is secured thereto, as bywelding. The unattached end of the iron core 56 is provided with anenlarged circular portion or pole 52, which may be integral therewith,and which extends into an aperture 54 provided in wall member 18. Theclearance between the rim of aperture 54- and the periphery of pole 52forms an air gap 55. The foregoing construction forms a magnetic circuitincluding magnet 48, wall member 16, wall member 18 and the air gap 55.The core 59 is hollowed axially longitudinally as by drilling to providea central open bore 56 therethrough. Back plate 16 is likewise drilledto provide an opening 58 located in registry with bore 56.

A movable cup-shaped coil form or support as, including parallel spacedapart flanges or rims 62, FIGS. 1, 2 and 5, forming an annular recesstherebetween, is provided with a plurality of turns of electricalconductors forming an energizing coil 63 disposed within the recess. Theends of the coil may be brought out along the flexible support member65, as shown in FIG. 5, for connection to a suitable source ofelectrical energy, not shown, in well known fashion.

Coil form ou is movably suspended within the air gap 55 by means of twosuspension members or swings 66 on opposite ends thereof, and which, inthe present iliustrated embodiment, may comprise light weight,resilient, rectangular flex-frames 68, of suitable material, such asmetal or plastic, supported in slotted mounting block 70, bolted torespective wall members 16 and 18. The two swings are interconnected bymeans of a tubular member 64 concentric with and extending through pole52;, by way of the bores 56 and 5'8. In this manner the coil 63 isprovided with a suspension having elastic axial freedom but which issubstantially rigid at right angles thereto. The degree of flexibilitymay be varied as required, by the design and material of the swingingframes 68.

The inner portion 69 of the hub of coil form 66 is drilled to receivethe tubular member 64. The hub extension 72' is drilled transversely andthe face thereof slotted to receive the mounting hinge 74 of a flatspring member 76, as shown most clearly in FIG. 5. Spring member 76 isprovided with a U-cutout 78 providing a fiat tang or tab 30 projectinginto the opening thus provided.

A yoke-shaped escapement wheel pawl, latch or shuttle, hereinafterreferred to as a latch 82 (FIG. 6) of relatively rigid but substantiallylight weight construction is secured by means of a rivet 84 to theunderside of the tab 86 with its principal or longitudinal axis in linewith the tab. A thin, light weight and relatively flexible strap 114 isattached to the upper surface of tab 80, the purpose of which will beexplained later. Latch 82, notched as at 85, straddles the escape wheel20 and its sides 86 and88 are chamfered to match the trailing portions87 of the escape wheel teeth. The rest or neutral position of latch 82,coil 63 and coil suspension 68 with respect to wheel 20 may be chosen,as shown in FIG. 4A, such that the latch is disposed with each sidethereof in the path of its associated set of escape teeth 24. With theapplication of a current pulse to the coil 63 in the proper direction,as will be explained later on, the latch 82 will move to the leftpermitting one tooth (the left) to escape as shown in FIG. 4B. The wheelis, however, promptly arrested by the opposite edge 88 of notch engagingan alternate tooth of the escape wheel. FIG. 4C shows the right handtooth engaged, while the left hand edge 86 of the notch is clear of itstooth. With the current off, the latch will return to its neutral, restposition still restraining the wheel. Pulsing the coil in the oppositedirection will cause the latch to shuttle to the right permitting onetooth on the right side to escape and engaging the alternate tooth onthe left side. The wheel 20 is thus permitted to step along one half thecircular pitch with each pulse reversal. Another mode of operation maybe obtained wherein the rest position of the latch 82 is either fully tothe right or to the left position resulting in the full engagement ofthe latch with a tooth. In this mode of operation pulsing the coil inthe proper direction will allow the wheel to step two teeth in two equalsteps per pulse, one step each for on and off, or make and break theapplied current.

In a manner to be explained presently the long tooth 26 is adapted toabut the inner edge 86 of latch 80 and in this manner provides a meansfor detenting the escape wheel in its home position. It should beapparent from the foregoing that by virtue of the notch 85 in the latch80 each time coil 63 is energized and de-energized the latch will bemoved axially of shaft transversely across the teeth of the escapementwheel permitting one tooth at a time to escape as clearly shown in thethree views of FIG. 4 allowing the shaft 10 to rotate through an arcuateincrement equal to the angular space between teeth 24 on opposite sidesof the wheel.

Escapernent wheel latch 82 is swingably mounted for movement in ahorizontal direction transverse to the direction of movement of wheel20, FIG. 1, by means of a pair of support or swing members 90-80, FIGS.2 and 5, which may be of light weight tubular construction. Each supportmember 90 is provided with a flexible wire-like element 92, FIG. 3,extending away from the opposite ends thereof. One end of each member 90may be secured to the latch by introducing the wire elements 92 thereofinto holes provided in the latch and peening over the ends of therespective wires 92. The oppositeend of each swing member is fastened bymeans of itsrespective wire 92 in a similar manner to a projection orpost 94 extending outwardly away from the wall member 18. By virtue ofthe foregoing construction the latch is permitted a freedom of movementin a direction parallel to the shaft 10 while being rigidly restrainedin a direction longitudinallyv of each support member 90 as' seen inFIG. 3.

Assuming that the output shaft'10 is under a rotative load from inputshaft 30 through the coupling 28, it is apparent that without more, thelatch 82 will restrain the escapement wheel 20 by abutting a tooth onone or the 7 other side of the escapement wheel, as shown in FIG. 6.

If now an electrical signal in the form of a current pulse, for example,is applied over the conductive leads 96 to the electrical windings ofthe coil 63, the coil form will be caused to move at extremely highspeed in much the same manner as the high frequency movement of themoving voice or voice coil of a radio loud speaker. By alternatelyreversing the current direction through the coil 63, coil form 60 can beattracted and repelled, back and forth within the air gap thus movingthe latch 82, as seen in FIG. 6, from its full line to its dotted lineposition and vice versa as indicated by the two-headed arrow 98. Thisvoice coil-like movement of the latch 82 permits the escapement wheel 20to step one projection or tooth at a time as each pulse is applied tothe coil 63. Thus it is seen that an extremely high frequency, highspeed step-bys'tep, low inertia, escapement type mechanism is providedin which a source of constant torque is applied to a rotative memberwhich is detented and periodically released in response to theapplication of controlled electrical signal pulses. 7

As before mentioned, depending upon whether the electrical current isapplied in a clockwise or counterclockwise direction, coil form 60 willbe oscillated to the left or the right, as viewed in the drawings. If itis inconvenient in a particular application to provide means for causingthe current to'be periodically reversed, the construction of FIG. 1 maybe modified so that the coil form 60 is biased in one direction only,e.g., by means of the member 66, in which case the electrical currentpulses are then applied in a direction such as to move the coil form andthus latch is biased.

restore it to some preselected position.

In apparatus such as that described hereinabove, it may be desirable tohome or zeroize the mechanism, i.e., A novel means for performing suchzeroizing function is illustrated in FIGS. 1 and 3. Referringparticularly to FIG. 3 there is provided a reset mechanism including arelay type electromagnet 102 suspended by means of a substantiallyU-shaped supporting bracket or frame member 104. Frame member 104 may besuitably mounted to the wall member 18 as by bolts and nuts. Thearmature or clapper 106 of the electromagnet 102 is pivotally mounted toone side of the frame member 104, as indicated at 107,

and is biased by means of a spring 108 away from its pole piece 110 andinto engagement with a limit member The elongated semi-rigid yetsuitably flexible member or strap 114, earlier referred to herein, ispivotally mounted at one end to the armature 106 as indicated byreference character 116. The opposite depending end of the strap 114 issecured to the tab 80 of the spring leaf 76 by means of the rivet 84. Inorder to reset the step-bystep mechanism including the escapement wheel20 to its zero or home position, the electromagnet 102 is energized overthe leads 118 from a source of electrical energy, not shown, therebyattracting the armature 106 to its pole piece 110 whereupon the strap114 lifts spring leaf 76 arcuately, vertically in FIG. 2. This movementof strap 114 is of sufficient extent to draw the latch 32 upwardly outof the path of movement of the tooth-like projections 24 on theescapement wheel, but not out of the path of movement of the high tooth26. If the escapement wheel 20 is now rotated under the urging of theconstant torque through coupling 28, the high tooth 26 will be broughtinto abutment with latch 82 abruptly stopping the wheel 20 inits zero orhome position.

In FIGS. 1 and 3 a commutator type rotary switch structure 120 is shownoperatively coupled to the novel stepping mechanism aforedescribed.Attached to the member 18, as by hollow spacers or pedestals 121 ofvarying extent, are a plurality of thin planar circuit members 122-422,the latter being supported in parallel spaced apart relation on thepedestals 121-121 by means of bolts 124 projecting outwardly away fromthe member 18 and nuts 126 threaded on the free ends thereof.

The circuits for the members 122-122, which may be fabricated by any ofa number of well known Ways, such as by printed circuit techniques, aremounted with their respective electrical circuit portions in confrontingface to face relation as seen in FIG. 3. It is to be understood thatneither the specific circuit resulting from the etching technique usednor the etched circuit construction generally forms any part of thepresent invention but is used herein solely as an illustration of oneform of commutator type switch apparatus which may be employed with thepresent invention.

Prior to attaching the etched circuit members to the spacing supports121, shaft 10 is provided with an electrically insulating hub member128, FIG. 1, secured thereto in a conventional manner as by key and keyway, or dowel pin, etc., not shown, for rotation therewith. The hub 128carries on each opposite side or face thereof an individual electricallyconductive double armed commutative wiper member 130. The oppositelyextending arms of wiper members 130 are each provided with bifurcatedcontact members 132 bent outwardly at right angles away from the centralportion of the end of each arm so as to be pressed lightly but firmlyagainst the confronting surface of a respective member 122-122.

As seen most clearly in FIG. 3, each etched circuit member 122 may beprovided with a plurality of radiating spoke-like conductive busses 134and an annular con ductive buss 136 forming a common electricalconnection therefor The length of the wiper arms 130 are chosen suchthat one arm of each double armed member is slightsunr ses 1y shorterthan the other opposite arm and rides on the common buss 136 while theother arm of the same wiper rides successively over each radiating buss134, as the shaft 10 is rotated thus to successively close differentcircuits associated therewith.

In the present application there has been described a novel step-by-stepmechanism which receives its driving torque from a constantly rotatingexternm source of power. The torque is applied through a yieldingcoupling to a shaft carrying the apparatus it is desired to control indiscrete steps. A moving coil-actuated low inertia shuttle typeescapement mechanism provides instantane ous, momentary step-by-stepadvancement of the shaft and associated apparatus without appreciablyaffecting the primary driving source, while at the same time permittingextremely high speed stepping operation. It is to be noted that thepresent invention is, or may be, asynchronous in its operation in thatthe electrical impulse energy applied to the control elements of themechanism can occur at any particular rate, random or otherwise, and themechanism will he stepped in accordance therewith. Finally,

the present invention provides a practical novel reset or zeroizingmechanism which may be actuated from any position of the escapementwheel at any desired time.

What is claimed is:

1. High speed stepping apparatus comprising in combination, a pair ofparallel spaced apart magnetic wall forming members, one of said membershaving an aperture therethrough, a rotatable shaft journalled betweensaid wall members, means coupling said shaft to a source of constanttorque, a toothed escapement wheel disposed on and rotatable with saidshaft, a cylindrical magnetic member disposed between said wall membersand including an axially aligned magnetic core, one end of said coreextending into said aperture and forming an air gap between said coreand the rim of said aperture, an electromagnetic member surrounding thesaid one end of said core and movable back and forth within said airgap, a latch for said escapement wheel, means operativelyinterconnecting said latch to said electromagnetic member, and meansconnecting said electromagnetic means to a source of electrical energywhereby upon energization and de energization of said electromagneticmeans said latch is engaged and disengaged with said escapement wheelthus permitting said wheel to be rotated step-by-step in response to theapplied torque.

2. High speed stepping apparatus comprising in combination, a rotatableshaft, means releasably coupling said shaft to a source of constanttorque, an escapement wheel rotatable with said shaft, said escapementwheel including a plurality of oppositely disposed oif-set peripheralrows of tooth-like projections, a latch movable transversely andalternately into and out of engagement with the peripheral projectionson said rows, electromagnetic means for so moving said latchtransversely of said wheel whereby said wheel is pe itted to step inindividual discrete increments in response aid constant torque, stopmeans on said wheel engageable ith said latch, and electromagnetic meansoperatively connected to said latch for disengaging said latch from saidperipheral projections while causing said latch to engage said stopmeans in a home position as said wheel is rotated whereby said wheel isrestrained from rotation.

3. High speed stepping apparatus comprising in combination, a rotatableshaft, a slip clutch coupling said shaft to a source of constant torque,an escapement wheel having peripheral rows of teeth on each facethereof, the teeth on one face being radially off-set with respect tothe teeth on the other face, a latch straddling said wheel and operablealternately to engage the teeth in each row to detent said escapementwheel, means to move said latch transversely of the plane of rotation ofsaid wheel to cause said latch to engage and disengage opposite off-setteeth thus permitting said wheel to rotate therepast one tooth at a'timein response to the application of said constant torque, and a resettingmechanism for said apparatus, said mechanism including detenting meanscarried by said escapement wheel, and electromagnetic means engagingsaid latch and responsive to the energization of said last means forretracting said latch out of the path of movement of the teeth of saidescapement wheel during rotation thereof to a reset position and intoengagement with said detenting means when it has reached its resetposition.

4. High speed stepping apparatus comprising in combination, a rotatableshaft, an electromagnetic clutch coupling said shaft to a source ofconstant torque, an escapement wheel disposed on said shaft androtatable therewith, electromagnetic means having an electrical signalresponsive element, and an escapement latch engagcd by said signalresponsive element and movable in response to movement of said element,said escapement latch including oppositely disposed substantiallyparallel projecting portions thereon adapted to alternately engageopposite sides of said escapement wheel thus to stop said wheel afterpredetermined increments of rotation thereof in response to said appliedtorque each time said electromagnetic means is energized, means to resetsaid escapement wheel to a home position, said reset means including anelectromagnet having a clapper, a member operatively connected to saidescapement latch and pivotally mounted to and moved by said clapper, andmeans on said escapement wheel adapted to be releasably engaged anddisengaged by said reset means in response to the energization andde-energization of said electromagnet thereby to reset said escapementwheel.

5. High speed step-by-step switching apparatus comprising, incombination, a rotatable shaft, a magnetic hysteresis clutch couplingsaid shaft to a source of constant torque for conjoint rotation, anescapement wheel fixed to and rotatable with said shaft in response tothe application of said torque to said clutch, said escapement wheelhaving integral oppositely disposed peripheral rows of tooth-likeprojections thereon, said wheel further including a reset projection ofgreater extent than said tooth-like projections, a magnetic memberprovided with an axial bore adapted to receive a movable element therethrough, a movable element receivable through said bore, a cup-shapedcoil carrying member including a coil thereon receivable over one end ofsaid magnet and secured to said movable element, suspension meansoffering low resistance to axial movement of said element and beingrigid in all other directions, attached at opposite ends of saidelement, a latch member coupled to and movable with said movable elementreleasably restraining said escapement wheel, and ,means to withdrawsaid latch from restraining engagement with the peripheral projectionson said escapement wheel and into the path of movement of said resetprojection thereby permitting said escapement wheel to be rotated intoabutting engagement therewith thus resetting said escapement wheel, andmeans connecting said coil to a source of electrical energy.

6. High speed stepping apparatus comprising in combination, a rotatableshaft, an escapement wheel rotatable with said shaft, said escapementwheel being provided with oppositely disposed parallel peripheral rowsof toothlike projections, the projections of one peripheral row beingradially off-set with respect to the projections of the oppositeparallel peripheral row by one-half the circular pitch of theprojections of said one row, said wheel also being provided with a resetprojection extending away from one peripheral edge thereof, anelectromagnet including a core, supporting structure for said apparatuscooperative with said core to form an air gap, an electricallyenergizable member movable within said air gap, means connecting saidlast named member to a source of electrical energy to cause said memberto move within said airgap, a flexible suspension mounted to saidenergizable member, a resilient spring-like member pivoted to saidsuspension, a U-shaped shuttle carried by said spring-like member andadapted to straddle said peripheral row of projections, said U-shapedshuttle being releasably engageable with alternate rows of saidprojections upon energization of said electrically energizable memberthereby to permit said escapement wheel to escape therepast a tooth at atime, an electromagnet, an armature movable in response to theenergization of said electromagnet, means connecting said armature tosaid spring-like member, and, means connecting said electromagnet to asource of electrical energy whereby when said electromagnet is energizedsaid shuttle is released from engagement with the rows of projections ofsaid escapement wheel and moved'into the path of travel of said resetprojection of said escapement wheel thus to 1%) permit said escapementwheel to be reset and stopped at a desired position.

References Cited in the file of this patent UNITED STATES PATENTS765,678 Reddohl July 26, 1904 1,623,026 Cabezola Mar. 29, 1927 1,833,914Ruben Dec. 1, 1931 1,972,971 Barenyi Sept. 11, 1934 1,989,604 Poole Jan.29, 1935 2,546,729 De Miller Jan. 29, 1935 2,938,606 Passman May 31,1960 OTHER REFERENCES Scientific American, Supplement No. 1536, vol. 59,published June 10, 1905, page 24617.

1. HIGH SPEED STEPPING APPARATUS COMPRISING IN COMBINATION, A PAIR OFPARALLEL SPACED APART MAGNETIC WALL FORMING MEMBERS, ONE OF SAID MEMBERSHAVING AN APERTURE THERETHROUG, A ROTATABLE SHAFT JOURNALLED BETWEENSAID WALL MEMBERS, MEANS COUPLING SAID SHAFT TO A SOURCE OF CONSTANTTORQUE, A TOOTHED ESCAPEMENT WHEEL DISPOSED ON AND ROTATABLE WITH SAIDSHAFT, A CYLINDRICAL MAGNETIC MEMBER DISPOSED BETWEEN SAID WALL MEMBERSAND INCLUDING AN AXIALLY ALIGNED MAGNETIC CORE, ONE END OF SAID COREEXTENDING INTO SAID APERTURE AND FORMING AN AIR GAP BETWEEN SAID COREAND THE RIM OF SAID APERTURE, AN ELECTROMAGNETIC MEMBER SURROUNDING THESAID ONE END OF SAID CORE AND MOVABLE BACK AND FORTH WITHIN SAID AIRGAP, A LATCH FOR SAID ESCAPEMENT WHEEL, MEANS OPERATIVELYINTERCONNECTING SAID LATCH TO SAID ELECTROMAGNETIC MEMBER, AND MEANSCONNECTING SAID ELECTROMAGNETIC MEANS TO A SOURCE OF ELECTRICAL ENERGYWHEREBY UPON ENERGIZATION AND DE-ENERGIZATION OF SAID ELECTROMAGNETICMEANS SAID LATCH IS ENGAGED AND DISENGAGED WITH SAID ESCAPEMENT WHEELTHUS PERMITTING SAID WHEEL TO BE ROTATED STEP-BY-STEP IN RESPONSE TO THEAPPLIED TORQUE.